Compound for tempering tools and tool steel



Patented Dec. 25, 1928.

UNITED STATES PATENT OFFICE.

JOHN F. EDWARDS, OF WARREN, ARKANSAS.

No Drawing.

A solution this compound is somewhat effective 0 in tempering but by theaddition of such other ingredients to these com ounds and by treatingthe tool in a very di ute bath steel of a high carbon content maybe'hardened by the usual quenching procedure to effect a fine, granulartexture containing the various carbides in proper proportion to renderthe tool effective and durable.

A tool treated by quenching in a bath containing the ingredients abovenoted and a density used for carbur'etting is too soft even whensulphate of copper is added to the bath as a hardener. I have discoveredthat the compound if used in a very dilute form gives v better results,but with the addition of other in redients which I have successfullyadded I lind that greatlyimproved results are obtained. The solution Ihave referred to as used for carburetting contains three ounces ofcommercial glycerine, one and a half ounces of spirit of nitre, one andone half ounces of aqua. ammonia,'two ounces of chloride of ammonia, oneand one half ounces of sulphate of zinc, one and one half ounces of 40sulphate of alumina and'auunoniaor alu-,

nnnuln ammonium alum dissolved in a half gallon of water.

A bath of these materials if used in the density employed forearburetting applied in hardening tool steel articles is not at alleffective leaving them too soft. If, however, the bath is diluted thehardening efiect begins to show and when it reaches the very high degreeof dilution taking only two to ounces of the mixture above described toa gallon of water better results in hardening Application filed December13, 1926. Serial No. 154,657;

may be effected. I have found now, however, that by adding to a solutionof this kind highly diluted one ounce of pure glycerine, one half ounceof table salt, one eighth ounce of copper sulphate andone halt ounce ofalum that the best results will be obtained. I have given the formulaemployed in the carburetting process to distinguish between a bath forraising the carbon content and a for mula suitable for tempering toolsteel which already has a high carbon content. According to myexperience the quality of glycerine 1s important, it being essential tobest results to employ pure glycerine. Some of the ingredients may bereduced or omitted but I have found that the addition of table salt andcopper sulphate in substantial proportion is important to successfulresults.

My invention therefore consists in a solution or bath for quenching toolsteel consistmg of a very dilute solution containing glyc-- erine,nit-re, ammonia, sal-ammoniae, alum and zinc sulphate to which is addedcommon salt, alum and copper sulphate in very much larger proportionsfor tempering. The implement or tool is brought to a chei'ry red andimmersed in the bath of the dilution described. It is then reheated to acolor depending on the temper desired, and chilled in pure water. i

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

A liquid bath for quenching tool steel, consisting of the followingingredients in the following approximate proportions:

Approximate metric equivalents. Glycerin 3 fluid ounces"- 96 c. 0. Sweetspirit of ultra I5 fluid ounccs 48 c. c. Anunonium (lll0llll0 1-; ounces48 gm. Zinc sulphate 1; ounces 48 gm. Aluminum and ammonium sulpli c 1ounw.-:.. i 48 gm. Water .s. gallon 2, 000 c. c.

of the foregoing .twofluid ounces is added to one gallon of watercontaining:

